I would prefer a lot less low mid on that piano, especially on the reverb frequencies, below 250 hz, and some more talking range frequencies, like 8k and above.
I might also cut the intro down by about half since it repeats the phrase 4 times. Same with the strings. Though you do differentiate them a bit more.
I might have made the entrances of each new phrase a bit more subtle, possibly used different string patches. If you don't have Kontakt, LABS, Pocket Blakus, etc., you may appreciate those slightly more realistic string libraries. A good flute alternative would be Egyptian Ney for Kontakt, also free last I remember. The temptation with soundfonts is to add superfluous reverb, which doesn't really add or take away from the obviously synthy sound.
Overall the piece is pensive and relaxing, but not quite subtle. There's a ton of reverb on instruments that naturally want to be a bit more dry -- like with those scratchy cello harmonics, and a flute melody that naturally would probably be best written for an ensemble with much, much softer intonation. Things that are very noticeable when we don't have extremely flexible instruments at our fingertips, i.e. soundfonts of real instruments. There's not a ton of harmonic movement or lead -- the piece doesn't lend itself to stepping out of the box of phrase A.
Overall, I enjoyed the listen, just some technical aspects to improve on. Don't worry, keep at it. The more you write, and the more you revisit your work, the better you'll be in the future. :)
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